In today's world, many electronic devices rely upon wireless connectivity for the reception of data from other connected devices. In a typical wireless deployment, there may be one or more wireless access points that transmit data, and one or more devices that receive data from the wireless access point(s).
In such a scenario, different devices may have different propagation channel characteristics, and these may affect their wireless data reception from the same wireless access point. For example, a device that is near the wireless access point and/or that has a fixed location (or is slowly moving) may have better propagation channel conditions than would a device that is moving at a high velocity and/or that is further away from the wireless access point. The first device may fall into a group of devices that can receive data encoded and transmitted with one set of parameters (such as a high Forward Error Correction (FEC) code rate, a high modulation level, and/or a smaller subcarrier spacing in an Orthogonal Frequency Division Multiplexing (hereinafter referred to as “OFDM”) system, while the second device may fall into a group of devices that need data to be encoded and transmitted with a second set of parameters (such as a low FEC code rate, a low modulation level, and/or a wider subcarrier spacing in an OFDM system).
There are many scenarios where a large number of devices may all wish to receive identical data from a common source. One such example is broadcast television, where a large number of television sets in various homes all receive a common broadcast signal conveying a program of interest. In such scenarios, it is significantly more efficient to broadcast or multicast the data to such devices rather than individually signaling the same data to each device. However, programs with different quality levels (e.g. high definition video, standard definition video, etc.) may need to be transmitted to different groups of devices with different propagation channel characteristics. In other scenarios, it may be desirable to transmit device-specific data to a particular device, and the parameters used to encode and transmit that data may depend upon the device's location and/or propagation channel conditions.
As described above, different sets of transmitted data may need to be transmitted with different encoding and transmission parameters, either simultaneously or in a time-multiplexed fashion (or both). The amount of data to be transmitted in a particular data set and/or the encoding and transmission parameters for that data set may vary with time.
At the same time, the demand for high-speed wireless data continues to increase, and it is desirable to make the most efficient use possible of the available wireless resources (such as a certain portion of the wireless spectrum) on a potentially time-varying basis.